The present invention relates to a grounding electrode of a process in which a moving web having a first side and a second side is arranged to serve as a substrate, and a powdery layer is arranged to be formed on the first side of the web by applying electrically charged particles on the web while the grounding electrode is arranged to be located at the second side of the web. The present invention also relates to a method for forming a powdery layer from powdery particles on a surface of a continuous web comprising steps of: Allowing the web having a first side and a second side to move between at least one charging unit of the powdery particles at the first side of the web, and at least one grounding electrode at the second side of the web being in a ground potential or another predetermined potential, applying on the first side of the web powdery particles, which are electrically charged in the charging unit, and finishing the powdery layer.
The known grounding electrodes used in this context have been stationary electrodes, such as electrically conductive plates.
A problem related to the method using the stationary grounding electrode with a moving web is that the particles of the dry powder tend to accumulate due to the stationary grounding electrode. The charged particles may tend to cake on the web at the location of the leaving edge of the grounding plate. A part of the charged particles remain in the sphere of influence of the grounding electrode, and do not move forward with the substrate. The phenomenon can be seen as a bubbling of the charged particles at the location of the edge of the stationary grounding electrode. As a consequence, an uneven powdery layer is formed on the substrate, and it can be seen as streaks on the surface of the substrate.